linux-old/include/linux/init.h
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   1#ifndef _LINUX_INIT_H
   2#define _LINUX_INIT_H
   3
   4#include <linux/config.h>
   5#include <linux/compiler.h>
   6
   7/* These macros are used to mark some functions or 
   8 * initialized data (doesn't apply to uninitialized data)
   9 * as `initialization' functions. The kernel can take this
  10 * as hint that the function is used only during the initialization
  11 * phase and free up used memory resources after
  12 *
  13 * Usage:
  14 * For functions:
  15 * 
  16 * You should add __init immediately before the function name, like:
  17 *
  18 * static void __init initme(int x, int y)
  19 * {
  20 *    extern int z; z = x * y;
  21 * }
  22 *
  23 * If the function has a prototype somewhere, you can also add
  24 * __init between closing brace of the prototype and semicolon:
  25 *
  26 * extern int initialize_foobar_device(int, int, int) __init;
  27 *
  28 * For initialized data:
  29 * You should insert __initdata between the variable name and equal
  30 * sign followed by value, e.g.:
  31 *
  32 * static int init_variable __initdata = 0;
  33 * static char linux_logo[] __initdata = { 0x32, 0x36, ... };
  34 *
  35 * Don't forget to initialize data not at file scope, i.e. within a function,
  36 * as gcc otherwise puts the data into the bss section and not into the init
  37 * section.
  38 * 
  39 * Also note, that this data cannot be "const".
  40 */
  41
  42#ifndef MODULE
  43
  44#ifndef __ASSEMBLY__
  45
  46/*
  47 * Used for initialization calls..
  48 */
  49typedef int (*initcall_t)(void);
  50typedef void (*exitcall_t)(void);
  51
  52extern initcall_t __initcall_start, __initcall_end;
  53
  54#define __initcall(fn)                                                          \
  55        static initcall_t __initcall_##fn __attribute_used__ __init_call = fn
  56#define __exitcall(fn)                                                          \
  57        static exitcall_t __exitcall_##fn __exit_call = fn
  58
  59/*
  60 * Used for kernel command line parameter setup
  61 */
  62struct kernel_param {
  63        const char *str;
  64        int (*setup_func)(char *);
  65};
  66
  67extern struct kernel_param __setup_start, __setup_end;
  68
  69#define __setup(str, fn)                                                                \
  70        static char __setup_str_##fn[] __initdata = str;                                \
  71        static struct kernel_param __setup_##fn __attribute_used__ __initsetup = { __setup_str_##fn, fn }
  72
  73#endif /* __ASSEMBLY__ */
  74
  75/*
  76 * Mark functions and data as being only used at initialization
  77 * or exit time.
  78 */
  79#define __init          __attribute__ ((__section__ (".text.init")))
  80#define __exit          __attribute_used__ __attribute__ (( __section__(".text.exit")))
  81#define __initdata      __attribute__ ((__section__ (".data.init")))
  82#define __exitdata      __attribute_used__ __attribute__ ((__section__ (".data.exit")))
  83#define __initsetup     __attribute_used__ __attribute__ ((__section__ (".setup.init")))
  84#define __init_call     __attribute_used__ __attribute__ ((__section__ (".initcall.init")))
  85#define __exit_call     __attribute_used__ __attribute__ ((__section__ (".exitcall.exit")))
  86
  87/* For assembly routines */
  88#define __INIT          .section        ".text.init","ax"
  89#define __FINIT         .previous
  90#define __INITDATA      .section        ".data.init","aw"
  91
  92/**
  93 * module_init() - driver initialization entry point
  94 * @x: function to be run at kernel boot time or module insertion
  95 * 
  96 * module_init() will add the driver initialization routine in
  97 * the "__initcall.int" code segment if the driver is checked as
  98 * "y" or static, or else it will wrap the driver initialization
  99 * routine with init_module() which is used by insmod and
 100 * modprobe when the driver is used as a module.
 101 */
 102#define module_init(x)  __initcall(x);
 103
 104/**
 105 * module_exit() - driver exit entry point
 106 * @x: function to be run when driver is removed
 107 * 
 108 * module_exit() will wrap the driver clean-up code
 109 * with cleanup_module() when used with rmmod when
 110 * the driver is a module.  If the driver is statically
 111 * compiled into the kernel, module_exit() has no effect.
 112 */
 113#define module_exit(x)  __exitcall(x);
 114
 115#else   /* MODULE */
 116
 117#define __init
 118#define __exit
 119#define __initdata
 120#define __exitdata
 121#define __initcall(fn)
 122/* For assembly routines */
 123#define __INIT
 124#define __FINIT
 125#define __INITDATA
 126
 127/* These macros create a dummy inline: gcc 2.9x does not count alias
 128 as usage, hence the `unused function' warning when __init functions
 129 are declared static. We use the dummy __*_module_inline functions
 130 both to kill the warning and check the type of the init/cleanup
 131 function. */
 132typedef int (*__init_module_func_t)(void);
 133typedef void (*__cleanup_module_func_t)(void);
 134#define module_init(x) \
 135        int init_module(void) __attribute__((alias(#x))); \
 136        static inline __init_module_func_t __init_module_inline(void) \
 137        { return x; }
 138#define module_exit(x) \
 139        void cleanup_module(void) __attribute__((alias(#x))); \
 140        static inline __cleanup_module_func_t __cleanup_module_inline(void) \
 141        { return x; }
 142
 143#define __setup(str,func) /* nothing */
 144
 145#endif  /* !MODULE */
 146
 147#ifdef CONFIG_HOTPLUG
 148#define __devinit
 149#define __devinitdata
 150#define __devexit
 151#define __devexitdata
 152#else
 153#define __devinit __init
 154#define __devinitdata __initdata
 155#define __devexit __exit
 156#define __devexitdata __exitdata
 157#endif
 158
 159/* Functions marked as __devexit may be discarded at kernel link time, depending
 160   on config options.  Newer versions of binutils detect references from
 161   retained sections to discarded sections and flag an error.  Pointers to
 162   __devexit functions must use __devexit_p(function_name), the wrapper will
 163   insert either the function_name or NULL, depending on the config options.
 164 */
 165#if defined(MODULE) || defined(CONFIG_HOTPLUG)
 166#define __devexit_p(x) x
 167#else
 168#define __devexit_p(x) NULL
 169#endif
 170
 171#endif /* _LINUX_INIT_H */
 172
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